Biamperometric Titration Research Articles

A novel cloud point back-extraction of uranium(VI) from organic radioactive solution to slightly acidic aqueous medium

ABSTRACT Stripping back uranium(VI) from an organic radioactive solution to an aqueous medium was rendered simple and quantitative by an unprecedented cloud point back-extraction (CPEback) method. The concentration difference of nitrate ions in and out of the micelle was employed to change the uranium distribution coefficient in favor of the bulk aqueous phase. In addition, the monophasic nature of cloud point extraction and the complexing ability of oxalic acid with uranyl ion in the bulk aqueous phase resulted in the quantitative recovery of uranium in a single step. The CPEback parameters were optimized through a cross-optimization process and the recovered uranium was quantified by the biamperometric titration method. The proposed analytical procedure resulted in high back-extraction efficiency and recovery of (99.6 ± 0.2)% and 99.2%, respectively. The process turned large volumes of organic radioactive solution into small volumes of a less hazardous organic medium having high viscosity and negligible vapor pressure. Analysis of two real samples of ~17 and 165 mL organic radioactive solutions resulted in 99% and 98.2% uranium recoveries, respectively. The leftover organic phase containing the extractant and nonionic surfactant can now be easily stored or reused.

Automatic Biamperometric Titration of Copper(II) by Iodide in Some Non-Aqueous Media

Automatic Biamperometric Titration of Copper(II) by Iodide in Some Non-Aqueous Media

A robust biamperometric titration methodology for the determination of uranium by Ti(III) reduction in the presence of plutonium

A biamperometric method is described for the determination of uranium in plutonium bearing nuclear fuel materials. Ti(III) is used for reducing U(VI) to U(IV) in 6 to 9 M H 2 SO 4 medium, followed by destruction of the excess reductant by HNO 3 . Plutonium is also reduced to Pu(III), but is selectively oxidized to Pu(IV) by the HNO 2 produced in situ during the destruction of the excess Ti(III) by HNO 3 . The U(IV) is determined by titration with standard K 2 Cr 2 O 7 . Accuracy and precision of the method have been evaluated using different amounts of uranium ranging from 5 microgram to 20 milligram. The method has been applied to U determination in uranium oxides, uranium carbides, (U, Pu)O 2 , (U, Th)O 2 , (U, Pu)C and U-Al alloy. The method has also been employed for the determination of U present at very low levels (< 0.2%) in PuO 2 .

Desenvolvimento de um procedimento biamperométrico para determinação de sacarina em produtos dietéticos

In this work was developed a method for the determination of saccharin in dietary products by a biamperometric titration, using two silver electrodes as working electrodes and silver nitrate as titrant. It were used products as juices (light) and sweeteners with saccharin in concentrations ranged from 8.73 x 10-5 mol L-1 to 1.0 x 10-2 mol L-1, and the results were in close agreement with those data found using a HPLC method at a confidence level of 95%. The main advantages of the proposed method are its simplicity, rapid and low cost.

Microanalytical Determination of Formaldehyde by Direct Titration with Hydroxylamine Using Interdigitated Microelectrode Array Biamperometric End-Point Indicator

An interdigitated microelectrode array (IDA) biamperometric titration is presented for the microdetermination of formaldehyde. It is based on a direct titration of formaldehyde with hydroxylamine under the formation of formaldoxime. The released hydrogen cations react with hydroxyl anions in 0.1 M NaOH. The interdigitated pair of two individually polarizable microelectrodes serves as a biamperometric end-point indicator. Hydroxylamine together with dissolved free oxygen behave as a quasi reversible mixed redox system, therefore a significant increase of current flowing between the IDA segments polarized by 100 mV is observed when the first excess of titrant appears in the titrated solution. Because of the small dimension of the IDA sensor this principle can be extended for a microanalytical variant of this method. Formaldehyde contents down to 10−3 M in small volume waste water samples could be determined by this technique. These samples usually contain carboxylic acids which interfere in iodimetric determinations, but do not influence the titration of formaldehyde with hydroxylamine.

AUTOMATED TITRATIONS WITH AN ALTERNATE FLOW, LINEAR SPEED, VARIATION SYSTEM. APPLICATIONS TO AMPEROMETRIC, BIAMPEROMETRIC, AND SPECTROPHOTOMETRIC TITRATIONS

ABSTRACT The “alternate flow” method was recently proposed as a solution to the problem connected to the requirement of frequent calibrations of systems utilizing peristaltic pumps. This method was successfully applied to amperometric titrations of the ferrous–ceric system, biamperometric titrations of arsenite–iodine and thiosulfate–iodine systems, and spectrophotometric titrations of ferrous–permanganate and arsenite–iodine systems. Equivalence point determination is possible in the micromolar range of concentrations. Titration times and sample volumes are of the order of 3 min and 3 mL, respectively; in titrations where the concentrations of sample and titrant solution are similar; results indicate accuracy better than 1%.

Biamperometric titration and flow injection determination of cyclamate in low-calorie products

Titration and flow injection (FI) methods with biamperometric detection at 0.7 V are proposed for determining cyclamate and are tested for various diet products. The titrant–reagent system was sodium nitrite in 1.0 mol l–1 phosphoric acid and there was no interference from glucose, fructose, sucrose, lactose, sorbitol, saccharin, benzoic acid, salicylic acid, fumaric acid, Sunset Yellow and Bordeaux-S. For the biamperometric titration method, the detection limit was 1.3 × 10–3 mol l–1 and the relative standard deviation (sr) was 1.0% for a solution containing 5.0 × 10–3 mol l–1 cyclamate (n= 9). The recovery of the sweetener from four low-calorie products ranged from 97.6 to 102.5% of the labelled amount. For the FI method there was a direct relation between cyclamate concentration and current decrease over 5.0 × 10–3 to 4.0 × 10–2 mol l–1 cyclamate with a detection limit of 2.5 × 10–3 mol l–1 and an sr of 1.7% for a solution containing 2.5 × 10–2 mol l–1 cyclamate (n= 10). Ninety results can be obtained per hour, and these, for various low-calorie products, are in good agreement with those obtained by a spectrophotometric FI method (r= 0.9993) and/or the labelled amount (r= 0.9937).

Automated gravimetric management of solutions. Part 1. High-performance microcomputer-controlled gravimetric burette

A versatile gravimetric burette and the necessary interface that allows it to be controlled by an IBM-PC microcomputer are described. The burette employs an electronic balance that holds three 30 ml flasks. The flasks are used for delivering different titrants or standard solutions and are connected to the sensor through the bottom of the balance. The addition of the solution is controlled by poly(tetrafluoroethylene) electromechanical valves housed inside the unit. The flasks can be refilled automatically from larger reservoirs placed outside the case. Solution level sensors are used to realize automatic refill when necessary. The mass delivered from the flasks is read by the computer through an RS232C interface. The burette can, when driven by the appropriate software, perform potentiometric, biamperometric and spectrophotometric titrations, standard additions procedures and the preparation of standard solutions.

Determination of uranium in the presence of iron and plutonium by Ti(III) reduction and biamperometric titration

A method is described for the determination of uranium in the presence of iron and plutonium. Ti(III) is used as the reductant in a mixture of H2SO4 and HNO3. Fe(II) and Pu(III) are selectively oxidized by the nitrous acid generated in the reaction between Ti(III) and HNO3. The U(IV) is determined by titration with K2Cr2O7 using biamperometry to detect the end point. The method is applicable to a variety of nuclear materials encountered at different stages of the nuclear fuel cycle and has no bias. The precision of the method is evaluated at different levels from 100 microgram to 100 milligram. The method is simple, rapid and convenient.

Biamperometric and Differential Pulse Polarographic Methods for the Assay of Nomifensine Maleate

Abstract Biamperometric titration and differential pulse polarography (DPP) are described for the analysis of nomifensine maleate powder and commercial capsules (MeritalR -50 mg). The biamperometric method involved the titration in cold dil. HCl medium against 0.01 M - NaN02 and electrometric detection of end point. The mean percent recoveries obtained were 100.0 ± 0.87 and 99.2 ± 0.95 for the authentic powder and capsules, respectively. The DPP method was performed by measuring the peak current, iP, obtained from the recorded differential polarogram under constant 50mV modulation amplitude. The peak current was measured at the peak potential of − 1.02 V on the dropping mercury electrode (DME) versus Ag/AgCl/KCl (sat.) reference electrode at pH 5.0 (acetate buffer). A linear relationship between peak current and concentration was demonstrated in the range 3 to 30μg ml−1. The mean percent recovery for the capsules was 103.1 ± 1.26.

Rapid and Simple Determination of Oxyphenbutazone in Dosage Forms by Biamperometric Titration

Oxyphenbutazone was determined in the presence of glacial acetic acid, hydrochloric acid, and potassium bromide by bromometric titration with biamperometric end point indication. The course of the titration was followed with double platinum electrode with 100 mV of polarizing voltage.

Oxidation of organic substances with compounds of trivalent manganese: XXIII. Preparation, stability, and determination of the titer of standard solutions of the fluoride complex of trivalent manganese

A method of preparation of 10 −2 −10 −3 M standard solutions of the fluoride complex of manganese(III) by the reaction of manganese(II) with permanganate in a medium of potassium fluoride acidified with sulfuric acid has been developed. It has been found that in a medium of 1 M sulfuric acid, 0.5 M manganese(II) sulfate, and 0.1 M potassium fluoride these solutions are sufficiently stable for both direct and indirect titrimetric determinations. The titer was determined using potassium iodide as a primary standard and potentiometric, bipotentiometric, or biamperometric titration.

Coulometric titration of some phenolic steroids with bromine based on thin-layer hydrodynamic biamperometric end-point detection

Four phenolic steroids were titrated coulometrically with bromine in a methanol—water solvent containing hydrochloric acid and sodium bromide. End-point detection was achieved with a twin electrode thin-layer cell placed in a flow loop connected to the titration vessel. Linear-segmented biamperometric titration curves were recorded. Concentrations of 17-β-estradiol were determined in the range from 442 ppb to 8.84 ppm with relative inaccuracies of -1.3% and +2.2%, respectively. Part-per-million solutions of estrone and estriol were titrated with good accuracy and precision. Somewhat poorer precision and accuracy was found for the determination of 17-α-ethynyl estradiol.

Electrometric titrations of Bi(III), Cu(II), Pt(IV), Te(VI) and Te(IV) with standard iron(II) solution in alkaline medla containing hexitols

Potentiometric, bipotentiometric and biamperometric titrations with an iron(II) salt in alkaline solutions containing sorbitol are reported. Suitable conditions are discussed for determinations based on the Bi(III) → Bi°, Cu(II) → Cu(I) → Cu°, Pt(IV) → Pt(II) → Pt° and Te(VI) → Te(IV) → Te° → telluride systems.

Electrometric titrations of Cr(VI), Mn(IV), V(V), Co(III) and U(VI) with a standard iron(II) solution in alkaline media containing hexitols

Direct and indirect potentiometric, bipotentiometric and biamperometric titrations with a standard iron(II) solution are described for some inorganic compounds in alkaline media containing hexitols (mannitol, dulcitol and sorbitol). The optimal conditions for titrations based on the Cr(VI) → Cr(III), Mn(IV) → Mn(III) → Mn(II), V(V) → V(IV), Co(III) → Co(II) and U(VI) → U(IV) systems are discussed. Of the hexitols studied, sorbitol has the greatest effect on the value of the redox potential of the Fe(III)/Fe(II) system; the Ef° value is about —1.10 V vs. SCE.

Indirect cerimetric determination of gold at the milligram level

A rapid volumetric method has been worked out for the indirect determination of 0.25–2.5 mg of gold in presence of many common ions. It is based on the reduction of gold(III) to metal with excess of cobalt(II) in the presence of 1,10-phenanthroline at pH 3 and 50°, and estimation of the unreacted cobalt(II) in the filtrate by visual, potentiometric or biamperometric titration with standardized cerium(IV) sulphate solution. It has been found that there is no interference from Ni(II), Pb(II), Zn(II), Cd(II), Mn(II), Mg(II), Ca(II), Al(III), Cr(III), Ti(IV), V(V) and W(VI). Interference due to Pd(II) and Ag(I) can be eliminated. Fe(III), Cu(II), Mo(VI), Hg(II) and Pt(IV) interfere, even present in small amounts.

Argentometric titration of halides in molten hydrated sodium acetate

Summary Potentiometric and biamperometric titrations of halide and silver ions have been carried out in molten hydrated sodium acetate at 360 K. Halide and silver ions were generated coulometrically. The titration error was always less than 2%. The solubility products of the silver halides were determined from the potentiometric data.

Biamperometric determination of platinum in some technical products

A method is described for the determination of platinum based on the reduction of platinum (IV) to platinum (II) with an excess of copper (I) chloride and titration of the resulting solutions with a strong oxidant, such as cerium (IV). The reaction proceeds in two steps, the first corresponding to oxidation of an excess of copper (I), and the second to oxidation of platinum (II). The electrochemical characteristics of the systems involved appear to be ideal for biamperometric titration. Up to the first end-point the reversible systems copper (II)-copper(I) is present, after which the next system, platinum(IV)-platinum (II), formed in the course of further additions of the titrant, is strongly irreversible. An excess of the oxidant in acidic solution forms a reversible cerium (IV)-cerium (III) couple. In these systems a double bend titration curve is formed when a small voltage (100 mV) is applied. The only standardised solution required is cerium (IV) sulphate and removal of oxygen is, in general, unnecessary. The reaction is much faster at elevated temperatures and it is therefore convenient to warm the solution up to 80 °C before titration.Depending on the concentration of the titrant (0·1 or 0·01 M) an amount of platinum from 5 to 50 mg can be determined with a relative standard deviation of about 0·14 per cent. This method has been applied to the determination of platinum in platinum-nickel alloys and platinum catalyst.

Biamperometric titration of hexacyanoferrate(III), iron(III), copper(II), cerium(IV), and iodine with mercury(I) perchlorate

The biamperometric titration of hexacyanoferrate(III), iron(III), copper(II), cerium(IV), and iodine with mercury(I) perchlorate has been studied. In the concentration range 50 to 1000 μ N, the error rarely exceeds 2 %. Although the biamperometric and R.P.E. amperometric techniques are of comparable utility at concentrations down to 100 μ N, the amperometric technique is preferable for low-concentration titrations.

Biamperometric Titration of Ferrous Iron and Cobah D. Singh, B. B. Prasad and Uma Bhatnagar

Biamperometric Titration of Ferrous Iron and Cobah D. Singh, B. B. Prasad and Uma Bhatnagar